Helically-configured barbed tape (the modern version of barbed wire) is often used about the perimeter of a secured area to prevent unauthorized entry into the area. The tape is in the form of a thin metal strip having a plurality of outwardly-extending barbs. In most applications, the tape is placed on a fence, wall or roof to enhance the impassibility of the existing barrier. In other applications, helicoidal barbed tape is used independently as a barrier.
There are two major weaknesses of barbed tape barriers that can be exploited by an individual who wishes to get past such a barrier. Firstly, the helical configuration of a barbed tape barrier is not extremely rigid and the loops of tape may be bent, flattened or spread apart using a wide board or similar object. Secondly, unless an alarm of some sort is combined with the barbed tape, a person may go undetected while employing a tool such as a bolt cutter or saw to cut through the tape and thereby remove it as an obstacle.
Many improvements have been made to barbed tape barriers to mitigate the above-noted weaknesses. The tape itself has been modified to include a center-located strengthening groove to improve its resistance to bending. In addition, there have been some attempts to add an alarm system to the barbed tape. In one example of such a system (Mainiero et al, U.S. Pat. No. 4,818,972), a vibration sensitive wire is incorporated within the tape and connected to a remote alarm unit.
Even with the above improvements, modern barbed tape barriers still suffer to some degree from many of the same problems as their simpler predecessors. The loops of the tape can still be flattened, bent or spread apart by an individual using a suitable tool. The alarm systems that are presently used in combination with barbed tape barriers are extremely expensive and their sensitivity is quite variable.